Found the case I was thinking of, it is a very interesting one. This can be distinguished in a number of ways, not least of all this was a very expensive heritage building, and the applicant wanted to install a complete elevator in the stairwell.
The key issue is reasonableness, i.e. if approval is not given, was the refusal to give approval unreasonable (the converse of that being that if there are reasonable grounds for refusing approval, then it is much more likely that the refusal would not be reversed)